Current version of localisation

• Primary sensory cortices: (visual, auditory, somatic sensory, olfactory and gustatory areas) are the first in line to receive information from peripheral receptors via the thalamus, with only a few synapses interposed.

• Higher order (secondary and tertiary) sensory cortices: they surround the primary sensory areas and integrate information coming from the psa's. In contrast, higher order motor areas send complex information required for a motor act to the primary motor cortex.

  Example of higher order sensory processing in vision is the detection of direction, intensity, contrast, speed, and other such combined attributes of stimuli. Here structural/ functional units like columns and modules have been found.

• Association cortices: carry out complex cognitive functions (sec. ). Functional units are hard to identify here.

• Broadly speaking simple sensory and motor functions are strongly localised while complex higher functions are the result of interconnections between various brain areas. However lesion, brain-imaging and single neuron studies have found localisation of some complex cognitive functions (sec. .

• Language is an example of a higher level function that is selectively carried out in one hemisphere while at the same time connections exist with the other hemisphere.

• Localisation is not static - functional area moves about during development and, to a lesser extent, afterwards (plasticity).

• ``Dynamic localisation'' - a lesion in a particular part of the brain in a child has a systematic effect on the cortical areas above it (thus lesions in sensory area have a more devastating effect in a child). A lesion in any region in an adult affects lower zones of the cortex which now depend upon it (thus for adults, lesions in the ACs, especially the frontal cortex are more devastating).

• A major problem with clinical studies is that most neurological syndromes are the result of interactions between two or more basic disorders - implies an analysis of the structure of the psychological processes and of experimental tasks is needed - this is where neuropsychology contributes. According to K&S, PNS, localisation studies have been held back due to the ``lack of a mature science of behaviour.''